Operating System Questions & Answers – Protection – Memory Protection

This set of 1000+ Operating System MCQs focuses on “Protection – Memory Protection”

1) What is true regarding ‘Fence’ ? (Choose 2)
a) Its a method to confine users to one side of a boundary
b) It can protect Operating system from one user
c) It can protect users from each other
d) It is implemented via software registerView Answer

Answer: a & b
Explanation: None.

2) What is not true regarding ‘Fence’ ?
a) It is implemented via hardware register
b) It doesn’t protect users from each other
c) It good to protect OS from abusive users
d) Its implementation is unrestricted and can take any amount of space in Operating system.View Answer

Answer: d
Explanation: None.

3) What is correct regarding ‘relocation’ w.r.t protecting memory ? (Choose 2)
a) It is a process of taking a program as if it began at address 0
b) It is a process of taking a program as if it began at address 0A
c) It changes all address to reflect the actual address at which program is located in memory
d) Fence cannot be used within relocation processView Answer

Answer: a & c
Explanation: None.

4) How can fence and relocation be used together ?
a) To each program address, the contents of fence register are added
b) To contents of fence register is subtracted from actual address of program
c) Both a and b
d) none of the mentionedView Answer

Answer: a
Explanation: This both relocates the address and guarantees that no one can access a location lower than a fence address.

5) What is basic need in protecting memory in multi-user environment ?
a) We need two registers one ‘start’ and other ‘end’
b) We need a variable register
c) A fence register has to be used known as base register.
d) none of the mentionedView Answer

Answer: c
Explanation: None.

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6) What is role of base/bound registers ?
a) They give starting address to a program
b) Program’s addresses are neatly confined to space between the base and the bound registers
c) They provide encrypted environment
d) This technique doesn’t protects a program’s address from modification by another userView Answer

Answer: b
Explanation: None.

7) What is all-or-nothing situation for sharing in memory ? (Choose 2)
a) Program makes all its data available to be accessed
b) It prohibits access to all
c) It creates rules who can access program memory
d) It separates program memory and data memoryView Answer

9) What is true regarding tagged architecture ? (Choose two)
a) Every word of machine memory has one or more extra bits
b) Extra bits are used to do padding
c) Extra bits are used to identify rights to that word
d) It is very compatible to code upgradesView Answer

Answer: a and c
Explanation: None.

10) What is best solution to have effect of unbounded number if base/bound registers?
a) Tagged architecture
b) Segmentation
c) Fence method
d) none of the mentionedView Answer

Answer: b
Explanation: None.

11) What is major feature of segmentation ?
a) Program is divided in data memory and program memory
b) Program is executed in segments
c) Program is divided into pieces having different access rights
d) It has effect of an unbounded architectureView Answer

Answer: a
Explanation: OS can retrieve the real address via looking for the table then making a simple calculation : address of the name + offset.

13) What is main objective of protection ?
a) Ensure all objects are protected individually
b) Objects have different priority and thus different levels of protection
c) Ensure that each object is accessed correctly and only by allowed processes
d) None of the mentionedView Answer

Answer: c
Explanation: None.

14) What is principle of least privilege ?
a) Less privileges provide difficulty in executing admin tasks.
b) Users can get temporary high privilege access
c) Users should be given just enough privileges to perform their tasks.
d) None of the mentionedView Answer

Answer: c
Explanation: None.

15) What is need of protection ? (Choose two)
a) Prevent mischievous and intentional violation
b) Prevent competitors to become better
c) Ensure that each program component uses resources allotted to it only.
d) For improving performance of systemView Answer

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